Gas discharge device



May 18, 1954 Filed April 9, 1953 E. O. JOHNSON ET AL GAS DISCHARGE DEVICE 2 Sheets-Sheet l 11 T'I'ORNE I E. O. JOHNSON ET AL GAS DISCHARGE DEVICE May 18, 1954 2 Sheets-Sheet 2 Filed April 9, 1955 llllh I, 9

.nllli llua a a INVENTORJ fawn/Pp .0. JOHNSON M72155 5. 0027/5 & M/c'mn ,4. 004 905440 ATTORNEY Patented May 18, 1954 GAS DIS CHARGE DEVICE Edward 0. Johnson, Princeton, and Charles E. Curtis and Michael A. Colacello, Trenton, N. .L, assignors to Radio Corporation of America, a

corporation of Delaware Application April 9, 1953, Serial No. 347,690

13 Claims.

This invention relates to gas discharge devices and particularly to improvements in such devices that are capable of conducting large magnitude currents.

In a copending application of E. 0. Johnson and W. M. Webster filed simultaneously herewith, Serial No. 347,689 and assigned to the same assignee as the present invention, there are described and claimed gas discharge devices which are capable of conducting large magnitude currents. As pointed out in the above-identified copending application, these gas discharge devices provide a very efficient type of device, or tube, for the conduction of high currents. This invention is an improvement in the electrode geometry of the gas discharge devices that are described in said copending application.

It is therefore an object of this invention to provide a new and improved gas discharge device.

It is another object of this invention to provide a new and novel arrangement of the electrodes in gas discharge devices.

It is a. further object of this invention to provide a new and improved gas discharge device that is capable of efficiently carrying high currents and is mechanically strong.

It is a still further object of this invention to provide a new and improved gas discharge device wherein the recovery time is greatly decreased.

It is a still further object of this invention to provide an improved arrangement of the auxiliary, or ionizing, electrodes in a continuously controllable gas discharge device.

These and other objects are accomplished in accordance with the general aspects of this invention by providing a gas discharge device enclosed within a sealed envelope having an ionizable medium therein. Within the envelope, all of the electrodes are supported externally to the space bounded by the active surfaces of the electrodes. The electrodes include a hollow open ended main thermionic cathode having an inwardly presented electron emissive surface; electrons being emitted from both of the open ends of the cathode. Adjacent each of the ends of the cathode is an apertured anode. Mounted to project electrons into the main dischargev space formed by these electrodes are a pair of auxiliary cathodes; one being mounted adjacent the aperture in each of the anodes on the side thereof away from the main cathode electrode. When desired, a pair of control electrodes are included one intermediate each end of said main cathode and each of said anodes. Th .zeqv iis itres hi li s i ev d to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself will best be understood by referring to the following description taken in connection with the accompanying drawings in which:

Figure 1 is a transverse sectional view of a gas discharge device constructed in accordance with this invention;

Figure 2 is an enlarged sectional view taken along line 2-2 of Figure 1; and

Figure 3 is an enlarged sectional view taken along line 3-3 of Figure 1.

Referring now to Figure 1 in detail, gas discharge device HJ comprises a gas tight envelope 1 l enclosing an ionizable medium. The envelope H is provided with the usual stem l2 through which lead-in conductors I3 are sealed in a conventional manner. The entire electrode assembly is supported by means of support rods [4.

The support rods [4 also function as conductors for the various electrodes when desired. In the center of the electrode structure (see Figure 2) there is a hollow, open ended, tubular shaped, main thermionic cathode [5 that has a corrugated cross section as shown. Wound around the outside of the thermionic cathode l5, preferably in the indentations thereof, is a heater element [6 that is coated with some type of insulating material. When desired, the outside of thermionic cathode l5 may be coated with an insulating material and an unshielded heater wire may be used.

concentrically spaced around the main thermionic cathode l5 are a plurality of heat shields it that are supported in spaced relationship by those support rods [4 connected thereto. The thermionic cathode I5 is preferably connected to the heat shields l8 so that during operation of the device ill, the cathode l5 and the heat shields [3 are at the same potential. Closely spaced adjacent each open end of the hollow tubular shaped main thermionic cathode I5 is a plurality of apertured end plates IQ for the heat shields 18. The end plates l9 extend inwardly toward the axis of the thermionic cathode l5 and terminate approximately at the inner circumference of the main thermionic cathode [5. The end plates l9 and the heatshields l8 may be made in one piece or may be constructed as separate elements.

Supported adjacent each of the end plates 19 isan apertured, disc shaped, control electrode 2| and 22, each having a plurality of rods 23 and 24 respectively which span the apertures therein. Each qfth'e' control electrodes 2| and 22 is sup- 3 ported in an insulated position by means of insulating rings around the support rods M as shown. The number and size of the control electrode rods 23 and 24 that span the apertures thereof is fairly important. If there is an insuricient number of control electrode rods, the deionization time of the device is relatively long. If the control electrode rods 23 and 24 are too numerous, or too large, the device is inefficient in that too large a percentage of positive ions are attracted to the control electrode rods during operation of the device. Since the number and size of control electrode rods 23 and 24 varies with the size of the device ID that is under consideration no specific examples are given although this is a consideration to be taken into account.

Connected to the outer periphery of each of the control electrodes 2i and 22 are a plurality of cooling fins 29. The cooling fins 29 extend toward opposite ends of envelope H in a direction away from main thermionic cathode i substantially parallel to the axis of the main cathode l5 and may be in the form of elongated ribbons of metal capable of good heat conduction and radiation. The cooling fins are for the purpose of radiating heat away from the control electrodes 2! and 22 so that the control electrodes never become hot enough to emit electrons even when device it is conducting extremely high currents.

A substantially cup-shaped anode 25 is mounted adjacent control electrode 2i, while a similar anode 25 is mounted adjacent control electrode 22. 25 is substantially the same as the circumference of main thermionic cathode l5. Each of the anodes 25 and 25 has an aperture :12 and 43 respectively in the closed end thereof, and each has a plurality of anode vanes 27 and 28 respectively connected thereto (see Figure 3). The vanes 2i and 28 are distributed radially about the axis of the anodes which are each coaxially mounted with main cathode l5. Vanes 2'! and 28 are for the purpose of increasing the amount of electron current collected by the anodes 25 and 26 for a given size anode in accordance with a copending application of L. Malter filed May 22, 1952 Serial Number 289,325 and assigned to the same assignee as the present invention. The I anodes are supported by the support rods l4 connected thereto and preferably have separate lead-ins so that each of the anodes 25 and 26 may be separately energized.

Spanning each of the apertures in the anodes 25 and 25 respectively, but insulated therefrom, is a mesh type constricting electrode 3& and 3i that is provided to improve the eiiiciency of the ionizing discharge. Each of the mesh type constricting electrodes completely spans the aperture in the anode adjacent to which it is mounted and is preferably connected to and supported by one of the apertured discs 32 and 33 as shown. The apertured discs 32 and 33 are supported by means of the support rods [4 in a conventional manner and are closely spaced to the anodes 25 and 25 respectively.

The device it is preferably a noise free type of discharge device as described in a copending application of W. M. Webster, E. 0. Johnson, and L. Malter, Serial Number 404,981 filed January 15, 1954 and assigned to the same assignee as the present invention. Therefore, tube H3 is preferably constructed so that the ratio of the arc drop across the device to the ionization po- The circumference of anodes 25 and 4 tential is less than 3, and the apertures in the apertured constricting electrodes 33 and 3| are no greater than the mean free path of the charged particles in the enclosed medium.

Supported adjacent each of the apertured constricting electrodes and 3| is an auxiliary cathode 35 and 36 respectively, each of which is arranged substantially perpendicular to the axis of the main thermionic cathode 15. Each of the auxiliary cathodes is supported in and surrounded by a shielding member 38 and 39 respectively. The purpose of shielding members 38 and 39 is to enclose the auxiliary cathodes 35 and 3G in such a manner that electron emission from the auxiliary cathodes is directed through the apertured constricting electrodes 30 and 31 into the region of the main group of electrodes. Inside each of the auxiliary thermionic cathodes 35 and 36 is a conventional heater element 40 and 4! respectively.

In operation of the device, a potential difference that is greater than the ionization potential of the enclosed medium is applied between the auxiliary cathodes and the main group of electrodes, 1. e. auxiliary cathodes 35 and 36 on the one hand and main thermionic cathode l5, control electrodes 2| and 22, and anodes 25 and 26 on the other. This potential difference causes an ionizing discharge to occur between the auxiliary cathodes 35 and 38 and the main group of electrodes; thus causing a plasma to be formed throughout the inside of the substantially hollow cylindrical space formed by the electrodes. The plasma provides a low impedance conducting path for the main current electrodes of the device it] as described more completely in a copending application of E. 0. Johnson Serial No. 185,745 and assigned to the same assignee as the present invention. A potential difference is i applied between the main thermionic cathode l5 and the anodes 25 and 26 that is less than the ionization potential of the enclosed medium and may be of the order of 2 to 4 volts. A signal is applied to the control electrodes 2i and 22. When these potentials are applied, a low impedance path is formed between the main current electrodes resulting in an extremely low arc drop across the main current electrodes and relatively high currents, i. e. as much as 10 amperes, can be efiiciently conducted through device 53. Even with such large currents the signal applied to the control electrodes 2| and 22 is capable of continuously controlling the flow of current from the main cathode I5 to the anodes 25 and 26 respectively.

When desired, each of the control electrodes 21 and 22, as well as each of the anodes 25 and 26, may be connected to different points in an external circuit so that two separate output currents may be utilized. When this is done, it is desirable to energize the auxiliary cathodes 35 and 3B in conjunction with their respective ends of the device Ill.

Due to the electrode geometry, the plasma formed throughout the inside of the electrode structure is conserved for a considerable length of time in that the positive ions that are in the plasma have no large areas to which they may diiiuse. As the number of control electrode rods 23 and 24 is increased, or the size of the rods 23 and 24 is enlarged, there will be an increased area that is attractive to the positive ions. As the number of control electrode rods 23 and 24 is decreased, then the deionization time of the device is relatively increased in that surfaces to 5 which-the positive; ions maydiffuse after the tube hasbeen cutoif are decreased and it is more difficult for the positive ion sheaths which extend from the negative grid wires during the recovery-to close off theopenings between these wires so that electron passage is prevented.

- Each of the auxiliary cathode shielding members -38-and 39 is preferably connected to one of the auxiliary cathodes 35 and 36 so that during operation the ionizing discharge takes place through the fine mesh electrodes 30 and 31 and in such a manner as to be more effective as described in the above-identified copending ap 'plication of E. 0.- Johnson, Serial Number 185 ,745, as well as to benoise free as described in the above-identified copending application of William M. Webster, E. 0. Johnson, and L. Malter, SerialNumber 404,981 filed January 15, 1954.

; -}Due to the arrangement of the auxiliary cathodes 35 and 36, theionizing discharge is located between the main group of electrodes in an effective manner. Due to the arrangement of the electrodes; the device is mechanically strong and may be easily transported without any danger of breakage. 5 I 7 It is believed obvious that though we have shown only one specific embodiment of our invention and have described our invention in connection therewith, an invention is subject to wide variations and modifications without departing from the spirit thereof. It is therefore intended to cover all such modifications which come within the scope of the appended claims.

We claim:

1. A gas discharge device, comprising a sealed envelope having an ionizable medium therein, a hollow open ended thermionic cathode within said envelope having emissive material on the inside and having corrugated inner and outer surfaces, a heater element wound around said cathode in the indentations of said corrugated surface but insulated therefrom, a heat shield concentrically mounted around said cathode and said heater element and having an apertured end plate on each end thereof extending toward the axis of said cathode, said heat shield being connected to said cathode, a pair of apertured control' electrode baffle members one spaced adjacent each end plate of said heat shield, control electrode wires spanning the aperture in each of said control electrode bafiie members, a plurality of heat radiation fins connected to the outer periphery of each of said baffle members and extending along the inside of said envelope away from said cathode, a pair of hollow tubular open ended anodes each having one open end arranged adjacent one of said baille members but insulated therefrom, a pair of apertured inwardly extending anode end plates one connected to the other end of each of said anodes, a plurality of anode vanes connected to each of said anodes and to their respective end plates, said anode vanes being disposed radially around the axis of said anode and extending theretoward, a pair of apertured constricting electrodes one extending across each of the apertures in each of said anode end plates and insulated therefrom, the apertures in said apertured constricting electrode being smaller than the mean free path of an electron in said ionizable medium, a pair of tubular auxiliary thermionic cathodes each being arranged substantially perpendicular to the axis of said hollow cathode and one arranged adjacent each of said apertured constricting electrodes on the side thereof removed from said hollow cathode, and a pair of substantially. cup-shaped auxiliary cathode shielding members eachsurr rounding one of saidauxiliary cathodesand con: nected thereto. a

2. A gas discharge device, comprising .alsealed envelope havingan ionizablemedium therein, a hollow tubular shaped open ended thermionic cathode within said envelope, said cathode ,having a corrugated outer surface, a heater element wound around said cathode in the indentations thereof but insulated therefrom, an emissive, ma.- terial on the inside of said cathode, .a hollow tubular shaped heat shield concentrically spaced around said cathode,v apertured endplates on said heat shield extending toward the axis of said cathode, a pair of apertured control electrode baflie members one adjacent each opening in each of said heat shield end plates, control electrode wires spanning the opening in each of said control electrode bafile members andconnected thereto, a pair of substantially cup shaped anodes each having the open end thereof arranged adjacent one of said control electrode baffle members, the end wall of each of said anodes having an aperture formed therethrough, a pair of auxiliary thermionic cathodes one arranged adjacent each of said, anodes on the. side thereof removed from, said hollow cathodaa pair ofaper: tured constricting electrodes one extending between each of said auxiliary cathodes and the aperture of the anode adjacent thereto, and a pair of auxiliary cathode shielding members each enclosing one of said auxiliary thermionic cathodes and open toward the apertured constricting electrode and anode adjacent thereto.

3. A gas discharge device, comprising a sealed envelope having an ionizable medium therein, a hollow open ended thermionic cathode having emissive material on the inside thereof within said envelope, a heater element wound around the outside of said cathode but insulated therefrom, heat shields spaced around said heater element, a pair of hollow tubular shaped anode members one adjacent each open end of said cathode, each end of said anodes remote from said cathode having a washer shaped anode end plate connected thereto, a washer shaped control electrode spaced intermediate each open end of said cathode and each of said anodes, a pair of mesh screens one across the opening in each of said anode end plates but insulated therefrom, and a pair of auxiliary thermionic cathodes one adjacent each of said mesh screens on the side thereof removed from said hollow cathode.

4. A gas discharge device, comprising a sealed envelope having an ionizable medium therein, a hollow tubular shaped cathode within said envelope, a pair of hollow tubular shaped open ended anodes of substantially the same diameter as said cathode, one open end of one of said anodes being arranged adjacent an open end of said cathode, one open end of the other of said anodes being arranged adjacent the other open end of said cathode, and a pair of auxiliary thermionic cathodes one arranged adjacent each of said anodes on the side thereof removed from said first mentioned cathode.

5. A gas discharge device, comprising a sealed envelope having an ionizable medium therein, an open ended tubular thermionic cathode supported within said envelope, the inner surface of said cathode being highly electron emissive, a pair of substantially cup-shaped anodes each having an aperture in the closed end thereof and each coaxially mounted with said cathode and with its open end adjacent to one open end of said cathode, and a pair of auxiliary cathodes each mounted adjacent said aperture in said closed end of one of said anodes on the side removed from said cathode.

6. A gas discharge device as in claim 5 further comprising a pair of control electrode members one intermediate each end of said cathode and each of said anodes.

'I. A gas discharge device as in claim 6 wherein each of said control electrode members have apertures therein and further comprising a plurality of control electrode wires spanning each of the apertures in each of said pair of control electrode members.

8. A gas discharge device, comprising a sealed envelope havin an ionizable medium therein, a hollow open ended tubular thermionic cathode supported within said envelope, a pair of auxiliary thermionic cathodes on spaced adjacent each open end of said hollow cathode, a pair of anode members each spaced intermediate said hollow cathode and one of said auxiliary cathodes.

9. A gas discharge device as in claim 8 further comprising a pair of apertured constricting electrodes each spaced intermediate one of said anodes and one of said auxiliary cathodes.

10. A gas discharge device as in claim 9 further comprising a pair of control lectrodes one spaced intermediate each of said anodes and an open end of said hollow cathode.

11. A gas discharge device, comprising a sealed envelope having an ionizable medium therein, a hollow open ended tubular thermionic cathode supported within said envelope, a pair of tubular auxiliary thermionic cathodes one spaced adjacent each open end of said hollow cathode, each of said cathodes having its axis arranged substantially perpendicular to the axis of said hollow cathode, a pair of hollow open ended anode members each spaced intermediate said hollow cathode and one of said auxiliary cathodes, and said anodes being substantially coaxially arranged With respect to said hollow cathode.

12. A gas discharge device as in claim 11 further comprising a pair of apertured constricting electrodes each spaced intermediate one of said anodes and one of said auxiliary cathodes.

13. A gas discharge device as in claim 11 further comprising a pair of control electrodes one spaced intermediate each of said anodes and an open end of said hollow cathode.

No references cited. 

